If you live in Preston and keep finding mould on your external walls — especially behind furniture or in cold corners — the root cause is usually cold bridging.
This happens when the wall loses heat faster than the room can replace it, causing condensation to form and feed mould growth.
At Weather Wise Solutions, we help homeowners understand why this happens and whether external wall insulation is the right long-term fix.
🧊 Why External Walls Get Mouldy
External walls are naturally colder than internal walls — but in older Preston properties, poor insulation and heat loss make the problem worse.
Mould often forms because:
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The wall is cold enough for moisture to condense
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The room produces more humidity than it can ventilate
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Furniture is pushed tight to the outside wall
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The wall is made from a material with poor thermal resistance
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Ventilation isn’t removing moisture fast enough
Even if you clean the mould, it returns because the surface temperature of the wall is still too low.
🧱 How External Wall Insulation Helps
External wall insulation (EWI) raises the surface temperature of the wall, meaning condensation is far less likely to form.
Here’s why it works:
1️⃣ Warmer Wall Surfaces
Thicker thermal layers stop heat escaping, eliminating the cold spots where mould thrives.
2️⃣ Reduced Cold Bridging
Weak points — such as concrete lintels, single-skin walls, or solid brickwork — no longer act as cold pathways.
3️⃣ Improved Energy Efficiency
Rooms stay warmer for longer, reducing heating costs and keeping humidity stable.
4️⃣ Long-Term Mould Prevention
When combined with correct ventilation, EWI can permanently stop black mould on external walls.
🌬️ Why Insulation Alone Isn’t Enough
Insulation reduces the risk of condensation — but it won’t stop mould unless airflow is also controlled.
That’s why we often pair EWI with:
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PIV systems to introduce filtered, low-humidity air
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DMEV fans for bathrooms, kitchens, and high-moisture rooms
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Humidity checks to ensure your home stays below dew-point thresholds
It’s the combination of warm walls + correct ventilation that delivers long-term results.
🛠️ Our Approach for Preston Homes
At Weather Wise Solutions Limited, we follow a structured, professional diagnostic process before recommending insulation or ventilation:
✅ Thermal imaging to identify cold bridging
✅ Moisture mapping to confirm the cause of mould
✅ Ventilation analysis to assess airflow rates
✅ External fabric inspection for cracks, render issues, or water ingress
We work with trusted suppliers including
PAM Ties and Wycamol to provide safe, breathable, and long-lasting solutions.
🏡 Why Preston Homeowners Choose Weather Wise
As a family-run damp and mould company, we take pride in providing honest advice — no upselling, no unnecessary work.
We’re proud members of:
Our CPD-qualified specialists offer insurance-backed guarantees on approved works, giving Preston homeowners complete peace of mind.
👉 Book your free mould and insulation assessment in Preston:
https://weatherwiseuk.co.uk/pages/contact